Tierra is a computer simulation developed by ecologist Thomas S. Ray in the early 1990s in which computer programs compete for central processing unit (CPU) time and access to main memory. At present, the commonly accepted definition of life does not consider any computer program to be alive, however, Tierra is a frequently cited[citation needed] example of an artificial life model; in the metaphor of the Tierra, the evolvable computer programs can be considered as digital ‘organisms’ which compete for energy (CPU time) and resources (main memory). In this context, the computer programs in Tierra could be considered evolvable and can mutate, self-replicate and recombine.<\/p>\n
Life on Earth is the product of evolution by natural selection
\noperating in the medium of carbon chemistry. However, in theory, the
\nprocess of evolution is neither limited to occuring on the Earth, nor
\nin carbon chemistry. Just as it may occur on other planets, it may also
\noperate in other media, such as the medium of digital computation. And
\njust as evolution on other planets is not a model of life on Earth, nor
\nis natural evolution in the digital medium.<\/p>\n
The Tierra C source
\ncode creates a virtual computer and its Darwinian operating system,
\nwhose architecture has been designed in such a way that the executable
\nmachine codes are evolvable. This means that the machine code can be
\nmutated (by flipping bits at random) or recombined (by swapping
\nsegments of code between algorithms), and the resulting code remains
\nfunctional enough of the time for natural (or presumably artificial)
\nselection to be able to improve the code over time.<\/p>\n
Along with
\nthe C source code which generates the virtual computer, we provide
\nseveral programs written in the assembler code of the virtual computer.
\nSome of these were written by a human and do nothing more than make
\ncopies of themselves in the RAM of the virtual computer. The others
\nevolved from the first, and are included to illustrate the power of
\nnatural selection.<\/p>\n
The operating system of the virtual computer
\nprovides memory management and timesharing services. It also provides
\ncontrol for a variety of factors that affect the course of evolution:
\nthree kinds of mutation rates, disturbances, the allocation of CPU time
\nto each creature, the size of the soup, etc. In addition, the operating
\nsystem provides a very elaborate observational system that keeps a
\nrecord of births and deaths, sequences the code of every creature, and
\nmaintains a genebank of successful genomes. The operating system also
\nprovides facilities for automating the ecological analysis, that is,
\nfor recording the kinds of interactions taking place between creatures.<\/p>\n
This
\nsystem results in the production of synthetic organisms based on a
\ncomputer metaphor of organic life in which CPU time is the “energy”
\nresource and memory is the “material” resource. Memory is organized
\ninto informational patterns that exploit CPU time for self-replication.
\nMutation generates new forms, and evolution proceeds by natural
\nselection as different genotypes compete for CPU time and memory space.<\/p>\n
Diverse
\necological communities have emerged. These digital communities have
\nbeen used to experimentally examine ecological and evolutionary
\nprocesses: e.g., competitive exclusion and coexistence, host\/parasite
\ndensity dependent population regulation, the effect of parasites in
\nenhancing community diversity, evolutionary arms race, punctuated
\nequilibrium, and the role of chance and historical factors in
\nevolution. This evolution in a bottle may prove to be a valuable tool
\nfor the study of evolution and ecology. <\/p>\n
taken from: http:\/\/life.ou.edu\/tierra\/<\/p>\n","protected":false},"featured_media":0,"template":"","artist":[106],"streams":[17],"keywords":[2279,2280,2278],"decade":[5543],"media":[5548],"class_list":["post-2599","document","type-document","status-publish","hentry","artist-tom-ray","streams-simulations-and-simulacra","keywords-artificial","keywords-life","keywords-simulating","decade-1990s","media-text"],"_links":{"self":[{"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/document\/2599","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/document"}],"about":[{"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/types\/document"}],"version-history":[{"count":0,"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/document\/2599\/revisions"}],"wp:attachment":[{"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/media?parent=2599"}],"wp:term":[{"taxonomy":"artist","embeddable":true,"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/artist?post=2599"},{"taxonomy":"streams","embeddable":true,"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/streams?post=2599"},{"taxonomy":"keywords","embeddable":true,"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/keywords?post=2599"},{"taxonomy":"decade","embeddable":true,"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/decade?post=2599"},{"taxonomy":"media","embeddable":true,"href":"https:\/\/artelectronicmedia.com\/en\/wp-json\/wp\/v2\/media?post=2599"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}